Low Noise Amplifiers (LNA) are often used in wireless communications to amplify weak received signals. However, when a strong radio-frequency (RF) signal is being received, an LNA may become unnecessary and can cause unwanted distortion in a receiver. To solve this problem, an LNA is sometimes used with a bypass switch configuration. A bypass mode allows an LNA to be digitally shutdown and simultaneously a bypass switch turned on, allowing a strong signal to go around the amplifier.
When using a field-effect transistor (FET) based LNA with a bypass switch in bypass mode, the FET can begin to be turned on as the high RF signal strength begins to modulate the gate of the FET. This unintended FET behavior causes unwanted distortion to be generated at the input and output of the LNA, potentially causing receiver signal corruption. This is a common issue with many examples of amplification circuits having bypass modes.
Accordingly, there is a need for an improved circuit or switching mechanism or other component that can address these problems associated with conventional devices.